The oculomotor cistern: anatomy and high-resolution imaging

Area of Science:

• Neuroradiology
• Neuroanatomy
• Neurosurgery

Background:

• The oculomotor cistern (OMC) is a cerebrospinal fluid (CSF)-filled dural cuff surrounding the third cranial nerve (CNIII).
• It serves as a crucial landmark for neurosurgeons operating within the cavernous sinus.
• Understanding OMC imaging is vital for managing cavernous sinus pathology.

Purpose of the Study:

• To present the imaging spectrum of the oculomotor cistern (OMC) on 1.5T and 3T MRI.
• To assess the OMC's visibility on routine and dedicated high-resolution MRI scans.
• To demonstrate the OMC's relevance in cavernous sinus pathology.

Main Methods:

• Retrospective review of 78 high-resolution MR images of the internal auditory canals (IAC).
• Measurement of OMC length and diameter.
• Evaluation of 50 whole-brain MR images for OMC visualization frequency.
• Dedicated high-resolution MRI in three volunteers for optimal OMC imaging.

Main Results:

• The OMC was visualized in 75% of IAC screening studies.
• Average right OMC length was 4.2 mm (diameter 2.2 mm); average left OMC length was 3.0 mm (diameter 2.1 mm).
• The OMC was identified on 64% of routine axial T2-weighted brain scans.

Conclusions:

• The oculomotor cistern (OMC) is a routinely identifiable landmark on dedicated thin-section, high-resolution MRI.
• It is also visible on a significant proportion of standard whole-brain MRI scans.
• The OMC is an important neuroradiologic and surgical landmark.